A Skinner box typically contains one or more levers which an animal can press, one or more stimulus lights and one or more places in which reinforcers like food can be delivered. The animal's presses on the levers can be detected and recorded and a contingency between these presses, the state of the stimulus lights and the delivery of reinforcement can be set up, all automatically. It is also possible to deliver other reinforcers such as water or to deliver punishers like electric shock through the floor of the chamber. Other types of response can be measured - nose-poking at a moving panel, or hopping on a treadle - both often used when testing birds rather than rats. And of course all kinds of discriminative stimuli may be used.